IY. 
DICT Y OTACEiE. — Punctaria. 
115 
1 . Punctaria tenuissima , Grey.; frond very thin, linear or linear-lanceolate, much 
attenuated to base and apex, flat or undulated. Grev. Alg. Brit. (1830) p. 54. 
Harv. Phyc. Brit. t. 248. Punctaria undulata, J. Ay. Sp. Alg. vol. 1, p. 72. Diplo- 
stromium tenuissimum et D. undulatum , Katz. Sp. Alg. p. 483. 
Hab. Parasitical on various Alga? near low-water mark ; as Zostera marina , Chor- 
da flum, dfc. Annual. Spring and Summer. — Halifax, W. H. H. Boston Harbour, 
G. B. Emerson. Little Compton, lb I., Mr. Olney , and Prof. J. W. Bailey. Fort 
Hamilton, N. Y., Mr. Hooper , dfc., W. H. H. (v. v.) 
This forms dense tufts extending for several inches along the leaves of the Zostera 
or the fronds of the Chorda on which they grow. Th q fronds are from two to eight 
or ten inches in length, and from a line to four or five lines in width, broadest in 
the middle, and tapering to both extremities. Some specimens are nearly linear 
throughout, except at the base or apex where they fine off ; but others are strictly 
lanceolate, very much attenuated from the middle towards the apex and the base. 
The margin in the young plant is quite flat ; and often remotely, but irregularly 
denticulate. In older specimens the frond is undulated, or crisped and often twisted 
spirally. The membrane is very thin, semitransparent, and delicate ; and the colour 
which is at first a pale greenish olive, becomes brownish or rather horn-colour in 
old plants. The fructification has not been observed. 
I retain Dr. Greville’s name for this plant, as being of earlier date than that 
assigned by Prof. J. Agardh ; who rejects Dr. Greville’s epithet from grounds which 
appear to me to be insufficient. The Zonaria tenuissima of the elder Agardh, which 
Dr. Greville takes as the type of his species, appears to have been founded (Sp. Alg. 
1. p. 138, and Syst. Alg. p. 268) on Ulva plantaginifolia var. tenuior , Lyngh. Hyd. 
Dan., p. 31, t. b.; and from Lyngbye’s figure and description there can be little 
doubt that Lyngbye’s and Greville’s plants were identical in species. Nay, this is 
admitted by Prof. J. Agardh, who quotes both these authors under his P. undulata ; 
but for some cause which I do not understand, he at the same time refers the 
synonym, “ Zonaria tenuissima , AgS to Laminaria Fascia. Yet, on referring to the 
Syst. Alg. where that name was first published, and from which Dr. Greville adopted 
it, we find the only synonym quoted is “ Ulva plantaginea var. tenuior , Lyngh. t. b.” 
but with a mark of doubt. On referring back to Agardh’s earlier work, the Sp. 
Alg. this same synonym is quoted without any doubt as the authority for Agardh’s 
‘‘ Zonaria plantaginea var. tenuior which is evidently the type of the subsequent 
“ Z. tenuissima .” Whether Agardh confounded young Laminaria Fascia also under 
this name is not to the point, as it is evident from his description and quotation that 
he intended by the name “ tenuissima , ” the “ U. plantaginifolia var. tenuior ” of 
Lyngbye ; and that is also the plant intended by Dr. Greville, and here described. 
I see no reason therefore for changing the older and very appropriate specific name 
into “ undulata .” 
2. Punctaria plantaginea , Grev. ; frond dark brown, coriaceo-membranaceous, 
